US3905701A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method and device for adjusting contrast in photographic and photomechanical reproduction work
Assignee: LOGABAX
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Filing: 1973-11-20
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Granted: 1975-09-16
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Expires: 1993-11-20
Abstract
Abstract This invention relates to photographic and photomechanical reproduction work, of the black-and-white or colour process type, and specially to new methods and means for adjusting the contrast between the lights and shades of the image. Basically, the auxiliary or flash exposure and the main exposure are adjusted and effected simultaneously, whereby the amounts of light transmitted by the shades and by the lights, respectively, of the original document have well-defined values. This is obtained by providing, in a photographic reproduction apparatus, a lens assembly comprising, adjacent the variable-aperture opaque diaphragm, a further variable-aperture diaphragm consisting of translucent material. The two diaphragms may have their control levers operatively interconnected for manual operation, or said diaphragms may be automatically operated by means of two photometers disposed in the lights and in the shades, respectively, of the image to be reproduced.
Inventors
- 👤 Michel David
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 12:30
CPC Classifications
G; G03; G03B; G03B27/00; G03B27/72; G03B27/80; G03B9/00; G03B9/08
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
181 words
Method of photographically reproducing an object, which comprises the following successive steps: a. forming a luminous reproduction beam propagating from the object in a predetermined direction; b. concentrating said light beam onto a plane surface disposed across said predetermined direction so as to form an image of said object thereon; c. stopping the propagation of said light beam outside a first closed contour disposed across said predetermined direction, and encompassing a first predetermined area; d. diffusing the portion of said light beam which passes between said first closed contour and a second closed contour disposed internally of the first one and encompassing a second predetermined area; e. varying simultaneously and in the same direction said first and second coutour areas respectively; f. measuring the illumination of the light areas of said object image; g. varying only said first contour area; h. measuring the illumination of the shade areas of said object image; i. repeating steps (e) to (h) until the illuminations measured in the light and shade areas of the image have predetermined values. j. photographing the image of said object.
Claim 2
Dependent Claim
181 words
Method of photographically reproducing an object, which comprises the following successive steps: a. forming a luminous reproduction beam propagating from the object in a predetermined direction; b. concentrating said light beam onto a plane surface disposed across said predetermined direction so as to form an image of said object thereon; c. stopping the propagation of said light beam outside a first closed contour disposed across said predetermined direction, and encompassing a first predetermined area; d. diffusing the portion of said light beam which passes between said first closed contour and a second closed contour disposed internally of the first one and encompassing a second predetermined area; e. varying simultaneously and in the same direction said first and second coutour areas respectively; f. measuring the illumination of the light areas of said object image; g. varying only said first contour area; h. measuring the illumination of the shade areas of said object image; i. repeating steps (e) to (h) until the illuminations measured in the light and shade areas of the image have predetermined values. j. photographing the image of said object.
Claim 3
Dependent Claim
140 words
Photographic reproduction installation comprising a reproduction apparatus equipped with a lens assembly, comprising a mount and, in said mount, at least one projection lens, a first variable-aperture diaphragm of opaque material and a second variable-aperture diaphragm of translucent material, said first and second diaphragms being disposed tandemwise in said mount in the optical field of said lens, and first and second means disposed on said mount for adjusting from the exterior the apertures of said first and second diaphragms, respectively, first and second photometers, disposed in one light area and one shade area of the image of the object to be reproduced, respectively, first and second power members for actuating said first and second means for adjusting the lens assembly diaphragm apertures, and first and second hand switchable electric means for selectively energizing saiD first and second power members, respectively.
Claim 4
Dependent Claim
140 words
Photographic reproduction installation comprising a reproduction apparatus equipped with a lens assembly, comprising a mount and, in said mount, at least one projection lens, a first variable-aperture diaphragm of opaque material and a second variable-aperture diaphragm of translucent material, said first and second diaphragms being disposed tandemwise in said mount in the optical field of said lens, and first and second means disposed on said mount for adjusting from the exterior the apertures of said first and second diaphragms, respectively, first and second photometers, disposed in one light area and one shade area of the image of the object to be reproduced, respectively, first and second power members for actuating said first and second means for adjusting the lens assembly diaphragm apertures, and first and second hand switchable electric means for selectively energizing saiD first and second power members, respectively.
Claim 5
Dependent Claim
154 words
Photographic reproduction installation comprising a reproduction apparatus equipped with a lens assembly, comprising a mount and, in said mount, at least one projection lens, a first variable-aperture diaphragm of opaque material and a second variable-aperture diaphragm of translucent material, said first and second diaphragms being disposed tandemwise in said mount in the optical field of said lens, and first and second means disposed on said mount for adjusting from the exterior the apertures of said first and second diaphragms, respectively, first and second photometers, disposed in one light area and one shade area of the image of the object to be reproduced, respectively, first and second power members for actuating said first and second means for adjusting the lens assembly diaphragm apertures, and electric means for energizing said first and second power members as long as the output signal of at least one of said first and second photometers departs from a predetermined value.
Claim 6
Dependent Claim
154 words
Photographic reproduction installation comprising a reproduction apparatus equipped with a lens assembly, comprising a mount and, in said mount, at least one projection lens, a first variable-aperture diaphragm of opaque material and a second variable-aperture diaphragm of translucent material, said first and second diaphragms being disposed tandemwise in said mount in the optical field of said lens, and first and second means disposed on said mount for adjusting from the exterior the apertures of said first and second diaphragms, respectively, first and second photometers, disposed in one light area and one shade area of the image of the object to be reproduced, respectively, first and second power members for actuating said first and second means for adjusting the lens assembly diaphragm apertures, and electric means for energizing said first and second power members as long as the output signal of at least one of said first and second photometers departs from a predetermined value.
Claim 7
Dependent Claim
43 words
Installation as set forth in claim 3, wherein said electric means for energising said power members comprises at least one Wheatstone bridge having two potentiometric arms, said bridge having input terminals connected to said photometers and output terminals connected to said power members.
Claim 8
Dependent Claim
69 words
Installation as set forth in claim 3, wherein said electric means for energizing said power members comprises a first and a second Wheatstone bridge, each having a potentiometric arm and another arm connected to said first or second photometer, a first and a second differential amplifier having input terminals connected to said first and second bridges, respectively, and output terminals connected to said first and second power members, respectively.
References Cited (Backward Citations)
US3528737A
Cited
US3784290A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-09-15 | 1979-03-17 | 1979-09-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-09-15 | 1983-03-17 | 1983-09-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-09-15 | 1987-03-17 | 1987-09-16 | $7700.00 | Window Closed / Lapsed |